Method for transporting, placing and compacting composite stiffeners

ABSTRACT

A device for compacting a contoured elongate composite layup includes flexible first and second fiber reinforced resin flexible sections flexible along their lengths. The first section is flexible within a first plane and the second section is flexible within the first plane as well as within a second plane.

BACKGROUND INFORMATION

1. Field

The present disclosure generally relates to the fabrication compositestructures, and deals more particularly with a method and device fortransporting, placing and compacting contoured composite stiffeners.

2. Background

During the fabrication of contoured composite stiffeners such asstringers, a compactor may be used to compact a layup of the stringeragainst tool surfaces. In some cases, the tool surfaces may be contouredalong one or more planes. Compactors have been developed that areflexible along a single plane of curvature, consequently where thestringer is contoured in more than one plane, the tool surfaces haverelatively complex geometries that require the compaction process to beperformed by hand. When laying up compound contoured composite stringersby hand, wrinkles may form in the laminate plies which gather at variouspoints in the layup and/or undesired fiber distortion may occur. Usinghand layup techniques, the location of ply wrinkles and ply gathering isdifficult to control, thus introducing variations in the finished partthat may affect part performance. Also, the human factor involved inhand layup may introduce process variations that lead to undesiredinconsistencies in the finished parts.

Accordingly, there is a need for a method and device for compactingcontoured composite stiffeners such as stringers which may consistentlyand predictably distribute ply wrinkles and gathering in a manner thatimproves part quality and/or performance. There is also a need for acompactor device that may be used to transport stringers to a cure tooland which conforms to compound curvatures of the stringer duringstringer placement and compaction.

SUMMARY

The disclosed embodiments provide a method and device for transporting,placing and compacting composite stiffeners, such as stringers, that arecontoured in more than one plane. The compactor places and compactsstringer layups in a cure tool in a manner that regulates andstandardizes the distribution of ply wrinkling and/or ply gathering. Thedisclosed compaction device is flexible in multiple planes and conformsto contours of the stringer regardless of undulations in stringergeometry. Predictable ply wrinkling/gathering allows engineering changesto be made in the stringer design which compensate for the ply wrinklingand/gathering, thereby improving part quality and/or performance.

According to one disclosed embodiment, a compactor is provided for usein fabricating a contoured elongate composite structure. The compactorcomprises at least a first section flexible along its length within afirst plane, and at least a second section coupled with the firstsection and flexible along its length within the first plane and withina second plane. The first and second planes are generally orthogonal toeach other. Each of the first and second sections includes a generallyplanar cap portion and a hat portion adapted to be received within acavity in the composite structure. The cap portion includes a pluralityof reinforcement strips extending transversely across the width of thecap portion and spaced along its length. The cap portion also includes aplurality of flexible rubber joints along its length which allow thesecond section to flex within the second plane. The hat portion includesa plurality of transversely extending slits therein which aresubstantially aligned with the flexible rubber joints.

According to another embodiment, a device is provided for transportingand compacting a contoured composite hat stiffener layup having a cavitytherein. The device comprises a hat portion adapted to be placed withinthe cavity, and a generally planar cap portion coupled with the hatportion and flexible within a first plane generally parallel to the capportion. The hat portion and the cap portion are each flexible in asecond plane generally orthogonal to the first plane. The cap portionincludes laminated plies of flexible material and strips ofsubstantially rigid reinforcement. The flexible material may comprise arubber.

According to a further embodiment, a method is provided of using acompactor to make a composite stiffener. The method comprises forming acomposite stiffener layup and bringing the compactor into contact withthe layup. The stiffener layup is adhered to the compactor, and thecompactor is used to transport and place the stiffener layup on asurface. The stiffener layup is compacted against the surface by thecompactor. Adhering the stiffener layup to the compactor includesgenerating a vacuum inside the compactor, and using the vacuum to suckthe stiffener layup against the compactor. Sucking the stiffener layupagainst the compactor includes generating a suction force by drawing airthrough sides of the compactor in contact with the layup. Using thecompactor to place the stiffener layup includes conforming the compactorto the geometry of the surface by allowing the compactor to flex withintwo generally orthogonal planes.

According to a still further embodiment, a method is provided of makinga compactor flexible in orthogonal planes for compacting a contouredcomposite stiffener layup. The method comprises laying up at least afirst portion of the compactor by placing a plurality of compositereinforcement strips in generally parallel, spaced apart relationship toeach other, and forming flexible joints between the reinforcement stripsby laminating a ply of flexible rubber with the reinforcement strips.The laminating includes cocuring the rubber ply and the reinforcementstrips. Laying up the first portion of the compactor includes providingat least one flat ply of fiber reinforced resin, castellating oppositeedges of the flat ply to form flange strips on the flat ply, and layingup the reinforcement strips over the flange strips.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the advantageousembodiments are set forth in the appended claims. The advantageousembodiments, however, as well as a preferred mode of use, furtherobjectives and advantages thereof, will best be understood by referenceto the following detailed description of an advantageous embodiment ofthe present disclosure when read in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is an illustration of a perspective view of a compactor accordingto one disclosed embodiment.

FIG. 2 is an illustration of a perspective view of a composite stringerattached to an aircraft skin curved in two planes.

FIG. 3 is an illustration of a side view of the stringer shown in FIG.2.

FIG. 4 is an illustration of a sectional view taken along the line 4-4in FIG. 3.

FIG. 5 is an illustration of a sectional view taken along the line 5-5in FIG. 3.

FIG. 6 is an illustration of an exploded, cross sectional view of a plylayup employed to form a section of the compactor shown in FIG. 1.

FIG. 7 is an illustration similar to FIG. 6 but showing a ply layupemployed to form another section of a compactor shown in FIG. 1.

FIG. 8 is an illustration of a plan view of a ply forming part of thelayups shown in FIGS. 6 and 7.

FIG. 9 is an illustration similar to FIG. 8, but showing opposing edgesof a portion of the ply having been castellated.

FIGS. 10-17 are illustrations of a plan views of a layup tool andsuccessive ply layup steps used to fabricate the compactor.

FIG. 18 is an illustration of a sectional view taken along the line18-18 in FIG. 1.

FIG. 19 is an illustration of a flow diagram of a method of fabricatingthe compactor.

FIG. 20 is an illustration of a cross sectional view of a hat stringerbeing vacuum bag formed over a male die.

FIG. 21 is an illustration of a sectional view of the hat stringerformed between male and female stamping dies.

FIG. 22 is an illustration similar to FIG. 21 but showing the compactorhaving been installed in the stringer layup.

FIGS. 23-26 are illustrations of sectional views showing successivesteps of transporting, placing and compacting the hat stringer in a curetool using the compactor.

FIG. 27 is an illustration of a flow diagram of a method for fabricatinga composite stringer.

FIG. 28 is an illustration of a flow diagram of aircraft production andservice methodology.

FIG. 29 is an illustration of a block diagram of an aircraft.

DETAILED DESCRIPTION

Referring first to FIGS. 1-5, a compactor 30 (FIG. 1) may be used totransport, place and compact a curved composite laminate stiffener, suchas without limitation, the contoured hat stringer 50 shown in FIGS. 2-5.The compactor 30 is generally semi-rigid, with a degree of flexibilitythat allows the compactor 30 to flex and conform to complex toolsurfaces (not shown in FIG. 1) during placement and compaction of astringer layup in the tool. During transport and placement of thestringer 50, the stringer 50 is held on the compactor 30 by a vacuumsuction force 31. The compactor 30 is elongate and broadly comprises afirst, segmented hat portion 38, and a second, continuous, generallyplanar cap portion 36. The hat portion 38 includes inclined side walls38 a and a bottom wall 38 b.

The cap 36 includes laterally extending flanges 36 a. The cap portion36, along with the hat portion 38 and a pair of end walls 45, form anenclosed interior space 35 extending substantially the entire length “L”of the compactor 30. A pneumatic fitting 42 in one or both of the endwalls 45 is adapted to couple the interior space 35 of the compactor 30with a suitable vacuum source (not shown) for drawing a vacuum withinthe compactor 30. As will be discussed below, the hat portion 38includes a plurality of generally parallel slits 40 therein which allowair to be drawn through the hat portion 38 into the interior space 35.The slits 40 extend substantially the entire height of the hat portion38 and divide it into individual segments 41 that allow the hat portion38 of the compactor 30 to flex during placement and compaction of thelayup in the tool. The slits 40 also allow air to be drawn into theinterior space 35, creating a vacuum 31 suction force that holds thestringer 50 on the compactor 30 during transport, placement andcompaction process. This vacuum adhesion of the stringer 50 to thecompactor 30 may permit a more symmetrical distribution of ply wrinklingand gathering during stringer compaction.

The compactor 30 includes at least a first single flexible section 32and at least a second double flexible section 34. The sections 32, 34are coupled with each other by joints 48 that are suitable for theapplication, such as, without limitation, splice joints, scarf joints orbutt joints. In the illustrated embodiment, the compactor 30 includesonly one section 34 coupled between two of the sections 32 by two joints48. However, the compactor 30 may have more than one of the sections 34located at any area along the length of the compactor 30, including oneither end of the compactor 30. In some embodiments, substantially theentire compactor 30 may comprise a double flexible section 34. Thecompactor 30 may have more or less than two of the single flexiblesections 32. As will be discussed later in more detail, section 34 ofthe compactor 30 includes flexible joints 23 that allow section 34 toflex in each of two planes 44, 46 that are substantially orthogonal toeach other. Plane 44 extends substantially parallel to and through thecap 36, while plane 46 extends substantially perpendicular to the cap36. The flexible joint 23 may also allow torsional twisting of thecompactor 30 along its longitudinal axis 47.

Both the cap portion 36 and the hat portion 38 may be formed fromlaminated plies (not shown in FIG. 1) of fiber reinforced resin, such aswithout limitation, carbon fiber epoxy. The number and thickness of theplies used to form the cap portion 36 in section 32 are chosen such thecap portion 36 is flexible within plane 44 to the degree necessary toallow the compactor 30 to conform with curved tool surfaces (not shown)during placement and compaction the stringer layup in the tool. Theslits 41 in the hat portion 38 allow the hat portion 38 to flex alongwith the cap portion 38 within the plane 44.

As will be described later, the area of the cap portion 36 that lieswithin the double flexible section of the compactor 30 is formed from acombination of materials that are cocured to form a plurality offlexible joints 23. These flexile joints 23 allow the cap portion 36 toflex within both planes 44, 46, as well as to twist about itslongitudinal axis 47. The slits 40 in the hat portion 38 also allow thearea of the hat portion 38 within section 34 to flex within plane 46. Asa result of the ability of the compactor 30 to flex within two planes44, 46 and conform to the geometry of a contoured tool 158 (FIGS. 24-26)or other surface during the stringer placement and compaction process,the location and/or pattern of ply gathering and/or ply wrinkling (notshown) may become more consistent, regular and/or predictable frompart-to-part, allowing suitable compensating engineering changes to bemade to the design of the stringer 50 which may improve the performanceof the stringer 50.

Referring now to FIGS. 2-5, the hat stringer 50 has a generally hatshaped cross section comprising a top 56, inclined side walls 55, a pairof laterally extending flanges 58. The stringer 50 may be attached tothe interior surface 52 a of a skin 52 having compound contours to whichthe stringer 50 may be required to conform. The flanges 58 of thestringer 50 may be secured to the skin 52 by any suitable means, such asfasteners (not shown), bonding adhesives or by co-curing the compositestringer 50 with the skin 52 in those applications where the skin 52 isa composite. As shown in FIGS. 2 and 3, the stringer 50 has a firstout-of-plane curvature 54, and as shown in FIG. 5 has a secondout-of-plane curvature 60 conforming to the compound contours of theskin surface 52 a.

Attention is now directed to FIG. 6 which illustrates a typical plylayup 61 used to form section 34 of the compactor 30 shown in FIG. 1.The layup 61 is formed ply-by-ply on a layup tool 65 having a cavity 66for forming the hat portion 38 of the stringer 50, and flange surfaces65 a for forming the cap portion 36. Two full width plies 64 of fiberreinforced resin are laid over the cavity portion 66 and covering theflange surfaces 65 a. Three additional plies 68 of fiber reinforcedresin are laid up within the cavity portion 66. In one embodiment, plies64 may be biased plies, while plies 68 may comprise a combination ofbiased plies and plain weave plies. The number of plies and their fiberorientations may vary, depending on the application.

A sixth ply 70 comprises a plurality of reinforcement strips 70 a ofunidirectional fiber reinforced resin which are spaced apart along thelength of the tool 65 and each have fiber orientations extendingtransversely across the cavity portion 66. The sixth ply 70 may compriseone or more stacked reinforcement strips 70 a of unidirectional prepregtape. A seventh ply 72 comprises a layer of flexible uncured syntheticrubber, such as, without limitation, Viton® fluoroelastomer, which has awidth slightly less than the strips in the sixth ply 70. The seventh ply72 may comprise other materials that remain flexible following curing.An eighth ply 74 comprises a second set unidirectional fiber reinforcedresin strips 74 a which cover the cavity portion 66 of the tool 65 andare respectively aligned with the strips 70 a forming ply 70, as will bediscussed in more detail below. A final ninth ply 76 comprises a secondfull width layer of flexible uncured synthetic rubber, which may also bea fluoroelastomer such as Viton®. The hat portion 38 of the layup 61 isformed by plies 64 and 68, while the cap portion 36 is formed by acombination of plies, 64, 70, 72, 74 and 76.

Referring to FIG. 7, the layup 63 forming section 32 of the compactor 30comprises a pair of full width plies 78 extending across the cavityportion 66 and over flange surfaces 65 a of the tool 65. Threeadditional plies 80 are laid up over the cavity portion 66. Next, a fullwidth ply 86 is laid up, followed by three plies 88 that cover only thecavity portion 66. Finally, another full width ply 90 is laid up. Eachof the plies of the layup 63 may be comprise a unidirectional or wovenfiber prepreg having fiber orientations selected for the particularapplication.

Attention is now directed to FIGS. 8-17 which illustrate the sequentialsteps used to form the layup 61 shown in FIG. 6. Referring first to FIG.8, a substantially flat layup 62 of plies 64 shown in FIG. 6 is providedwhich has a length substantially equivalent to that of all threesections 32, 34 of the compactor 30. Next, as shown in FIG. 9, theopposing edges 95 along compactor section 34 of the layup 62 arecastellated using any suitable material removal technique, such as,without limitation, die cutting. This castellation results in a seriesof reinforcement flange strips 64 a in each of the plies 64 which arespaced apart along the length of section 34 and are separated by slots128.

FIG. 10 illustrates the tool 65 ready to receive the ply layup 61 shownin FIG. 6. As previously mentioned, the tool 65 includes a hat shapedcavity portion 66 for forming the hat portion 38 of the compactor 30,and a pair of flange surfaces 65 a for forming the flange portions 36 aof the cap portion 36 of the compactor 30.

FIG. 11 illustrates the castellated plies 64 having laid up on the tool65, with the spaced apart flange strips 64 a overlying the flangesurfaces 65 a of the tool 65. FIG. 12 reflects completion of the nextstep in the layup process, in which the plies 68 are laid up within thecavity portion 66 of the tool 65, overlying plies 64. Then, as shown inFIG. 13, an inflatable bladder 142 is placed in the cavity portion 66,overlying plies 68.

Referring to FIG. 14, the next step in the fabrication process compriseslaying up the transversely extending unidirectional prepregreinforcement strips 70 a, in alignment with and overlying the flangestrips 64 a (FIG. 13) of the castellated layup 62. Each of thereinforcement strips 70 a may comprise one or more plies ofunidirectional prepreg tape, however other types of reinforcements maybe possible. The reinforcement strips 70 a span substantially the entirewidth of the cap section 36 and spaced on a pitch that is suited to theparticular application.

FIG. 15 shows rubber ply 72 having been laid up over the reinforcementstrips 70 a following which, as shown in FIG. 16, a second set ofgenerally parallel, spaced apart reinforcement strips 74 a are laid upover the rubber ply 72, aligned with both the underlying reinforcementstrips 70 a and the flange strips 64 a (see FIGS. 13 and 14). Thereinforcement strips 74 a reinforce the area of the cap section 36 thatoverlies the cavity 66. Finally, as shown in FIG. 17, a second ply 76 ofuncured synthetic rubber or similar flexible material is laid up overthe reinforcement strips 74 a. The second rubber ply 76 spanssubstantially the entire width of the layup 61.

FIG. 18 is a sectional illustration showing one of the flexible joints23 in compactor section 34. The aligned stacking of the reinforcementstrips 64 a, 70 a, 74 a forms slots 128 that are filled with rubber fromrubber plies 72, 76 during ply lamination of the cap portion 36.Following this lamination, the flexible rubber joints 23 extend acrosssubstantially the entire width of the cap portion 36. The reinforcementstrips 64 a, 70 a, 74 a provide the compactor section 34 with therigidity needed to maintain its shape and prevent it from collapsingwhen a vacuum is drawn within the compactor 30, while the rubber filledslots 128 forming joints 23 allow the cap portion 36 to flex withineither of orthogonal planes 44, 46 (FIG. 1). The flexible rubber joints23 are aligned to coincide with the location of the slits 40 along thelength of the compactor.

FIG. 19 is a flow diagram illustrating the steps of a method offabricating the compactor 30. In one embodiment, beginning at step 92, aflat layup 62 of plies 64 is provided, and at step 94 the edges of thelayup 62 are castellated. At 96, the castellated layup 62 is placed onand formed over a tool 65, and additional plies 68 may be laid up, asrequired, to reinforce the hat portion 38 of the compactor 30. Then, asshown at 106, an inflatable bladder 142 is installed in a cavity of thetool 65, overlying plies 64, 68. Alternatively, as shown at 100, plies64 may be laid up on the forming tool 65 without castellation, followingwhich additional hat plies 68 may be laid up at 102, as required. At104, the edges of plies 64 are castellated to form the reinforcementflange strips 64 a in double flex section 34 of the compactor 30. At108, the composite reinforcement strips 70 a are laid up over the flangestrips 64 a, and at 110 the first ply 72 of uncured rubber is laid upover the flange strips 64 a. At 112, the second set of unidirectionalcomposite reinforcement strips 74 a are laid up over the first rubberply 72 in order to further reinforce the area of the cap portion 36 thatoverlies the cavity 66. At 114 the second ply 76 of uncured rubber islaid up over the reinforcement strips 74.

Each of the compactor sections 32 is laid up by first laying up theplies of the hat portion 38 in step 116, and then laying up the plies ofthe cap portion 36 at step 118. As the cap plies of compactor section 32are being laid up, at least certain of these plies are interleafed withthe cap plies of compactor section 34, as shown at step 120, in order toform the overlapping splice joints 48 between compactor sections 32, 34.The joints 48 may reduce localized stiffness and increase the overalldurability of the compactor 30. As previously mentioned, although splicejoints 48 have been shown in the exemplary embodiment, other types ofjoints may be possible.

At 122, the compactor layup is vacuum bagged and the rubber andcomposite resin plies are co-cured, either with or without autoclaveprocessing. Following co-curing, the slits 40 in the hat portion 38 ofthe compactor 30 are formed by cutting, sawing, or other suitableprocesses. As previously mentioned, the slits 40 are located and spacedapart from each other such that they are substantially aligned with therubber filed slots 128.

Attention is now directed to FIGS. 20-26 which illustrate the steps of amethod of forming, transporting, placing and compacting a composite hatstringer 50 layup using the flexible compactor 30. Referring first toFIG. 20, a composite hat-shaped stringer 50 may be formed by placing amulti-ply composite charge over a male die 152 and using a vacuum bag153 to compact and form the charge over the die 152. Alternatively, asshown in FIG. 21, the stringer 50 may be formed by stamp forming acomposite charge between male and female dies 152, 156, respectively,creating a hat cavity 154. Following forming, the stringer 50 may betrimmed, as necessary. With the stringer 50 supported in the female die156, the compactor 30 is placed in the hat cavity 154 of the stringer 50such that the hat 38 portion of the compactor 30 engages sidewalls 55and the top 56 of the stringer 50, and the flange portions 36 a of thecompactor cap 36 overlie and engage the flanges 58 of the stringer 50.The stringer 50 and the compactor 30 may remain in the female die 156which may be used as a holding fixture to maintain the shape of thestringer 50 until the stringer 50 is ready to be removed and transportedfor placement. Optionally, the stringer 50 may be transferred to aholding fixture (not shown) until ready for placement. In order toremove stringer 50 from the female die 156 (or an optional holdingfixture), a vacuum is drawn within the compactor 30 which draws air inthrough the slits 40 (FIG. 1) to create a suction force 31 (FIG. 22)that causes the stringer 50 to adhere to the compactor 30.

As shown in FIG. 23, with the stringer 50 adhered to the compactor 30,the compactor 30 is lifted along with the stringer 50 away from femaledie 156, and is used to transport the stringer 50 to a structure such asthe tool 158, as shown in FIG. 23, having female tool surfaces 159 thatare curved in more than one plane and substantially match the outer moldline (OML) surface (not shown) of the stringer 50. The compactor 30 isused to place the stringer 50 in a cavity 160 of the tool 158, as shownin FIG. 25. With the compactor 30 and the stringer 50 installed in thetool cavity 160, a vacuum bag assembly 155 is installed over thecompactor 30 and the stringer 50, and a vacuum is drawn in the bag 155(FIG. 25) which, along with the compactor 30, compacts the layup 50against the tool surfaces 159. Following compaction of the stringer 50,as shown in FIG. 26, the compactor 30 is drawn away from the stringer50. The stringer 50 may then be further processed. For example, fillers(not shown) may be installed in the stringer 50, one or more bladders(not shown) may be installed against the stringer 50, the stringer 50may be attached to the skin 52 (FIG. 2) and cured in an autoclave (notshown), etc.

FIG. 27 illustrates a flow diagram of the steps of fabricating thestringer 50 previously described in connection with FIGS. 20-25.Beginning at 162, the composite hat stringer 50 charge is laid up and,optionally trimmed, as necessary. At 164, the stringer charge is formedinto a stringer shape, as by die stamping or other processes. The formedstringer 50 may be trimmed after it is formed in step 164, if notpreviously trimmed in step 162. Optionally, the stringer 50 may betransferred to a holding fixture until it is ready to be transported andplaced by the compactor 30. At 166, the compactor 30 is installed in thestringer cavity 160. The compactor 30 may remain in the stringer 50 tomaintain its shape until the stringer 50 is ready to be removed from thefemale die 156 or a holding fixture. At 168 the stringer 50 is adheredto the compactor 30 using a force generated by drawing a vacuum withinthe compactor 30 that sucks the stringer 50 against the compactor 30.Next, at 170, the compactor 30 is used to lift and transport thestringer 50 to a tool, fixture, part or other structure or surface. Forexample, and without limitation, the compactor 30 may be used totransport the stringer 50 to a tool 158, and then place the stringer 50at a desired location on the tool 158 or other structure or surface. Asthe stringer 50 is being placed by the compactor 30, the compactor 30may flex in either or both of two orthogonal planes 44, 46, or twistaround its longitudinal axis 47 (FIG. 1) to the extent necessary toconform the stinger layup 50 to the curved surfaces of the structure,such as the tool surfaces 159.

At 174, a vacuum bag 155 along with other usual bagging components (notshown) are installed and sealed over the tool 158, covering the stringer50 and the compactor 30. At 176, a vacuum is drawn on the bag 155 whichcompacts the stringer 50 through the compactor 50, while the vacuum ismaintained within the compactor 30. The vacuum drawn within thecompactor 30 may aid in evacuating the vacuum bag 155 during thecompaction process, as a result of air leaking into the compactor 30through the slits 40 (FIG. 1). At 178 the stringer layup is debagged,the vacuum within the compactor 30 is released, and the compactor 30 isremoved from the tool 158. At 180, the compactor may be staged for reusein compacting another stringer layup 50. The stringer fabricationprocess may be continued at 182, depending on the application, byinstalling fillers in the stinger 50, applying bladders, attaching skinsto the stringer, etc.

Embodiments of the disclosure may find use in a variety of potentialapplications, particularly in the transportation industry, including forexample, aerospace, marine, automotive applications and otherapplication where automated layup equipment may be used. Thus, referringnow to FIGS. 28 and 29, embodiments of the disclosure may be used in thecontext of an aircraft manufacturing and service method 184 as shown inFIG. 28 and an aircraft 186 as shown in FIG. 29. Aircraft applicationsof the disclosed embodiments may include, for example, withoutlimitation, layup of stiffener members such as, without limitation sparsand stringers. During pre-production, exemplary method 184 may includespecification and design 188 of the aircraft 186 and materialprocurement 190. During production, component and subassemblymanufacturing 192 and system integration 194 of the aircraft 186 takesplace. Thereafter, the aircraft 186 may go through certification anddelivery 196 in order to be placed in service 198. While in service by acustomer, the aircraft 186 is scheduled for routine maintenance andservice 200, which may also include modification, reconfiguration,refurbishment, and so on.

Each of the processes of method 184 may be performed or carried out by asystem integrator, a third party, and/or an operator (e.g., a customer).For the purposes of this description, a system integrator may includewithout limitation any number of aircraft manufacturers and major-systemsubcontractors; a third party may include without limitation any numberof vendors, subcontractors, and suppliers; and an operator may be anairline, leasing company, military entity, service organization, and soon.

As shown in FIG. 29, the aircraft 186 produced by exemplary method 184may include an airframe 202 with a plurality of systems 204 and aninterior 206. The airframe 202 may include various stiffeners such asstringers and spars that may be fabricated using the disclosed methodand compactor. Examples of high-level systems 204 include one or more ofa propulsion system 208, an electrical system 210, a hydraulic system212, and an environmental system 214. Any number of other systems may beincluded. Although an aerospace example is shown, the principles of thedisclosure may be applied to other industries, such as the marine andautomotive industries.

Systems and methods embodied herein may be employed during any one ormore of the stages of the production and service method 184. Forexample, components or subassemblies corresponding to production process192 may be fabricated or manufactured in a manner similar to componentsor subassemblies produced while the aircraft 186 is in service. Also,one or more apparatus embodiments, method embodiments, or a combinationthereof may be utilized during the production stages 192 and 194, forexample, by substantially expediting assembly of or reducing the cost ofan aircraft 186. Similarly, one or more of apparatus embodiments, methodembodiments, or a combination thereof may be utilized while the aircraft186 is in service, for example and without limitation, to maintenanceand service 200.

The description of the different advantageous embodiments has beenpresented for purposes of illustration and description, and is notintended to be exhaustive or limited to the embodiments in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different advantageousembodiments may provide different advantages as compared to otheradvantageous embodiments. The embodiment or embodiments selected arechosen and described in order to best explain the principles of theembodiments, the practical application, and to enable others of ordinaryskill in the art to understand the disclosure for various embodimentswith various modifications as are suited to the particular usecontemplated.

What is claimed is:
 1. A method of using a compactor to make a compositestiffener, comprising: forming a composite stiffener layup; bringing thecompactor into contact with the stiffener layup, wherein the compactoris defined by a longitudinal axis; adhering the stiffener layup to thecompactor; using the compactor to transport and place the stiffenerlayup on a surface; flexing the compactor within two generallyorthogonal planes intersecting along the longitudinal axis defining thecompactor to conform the compactor to the geometry of the surface; andusing the compactor to compact the stiffener layup against the surface.2. The method of claim 1, wherein adhering the stiffener layup to thecompactor includes: generating a vacuum inside the compactor, and usingthe vacuum to suck the stiffener layup against the compactor.
 3. Themethod of claim 1, wherein sucking the stiffener layup against thecompactor includes generating a suction force by draw air through sideson the compactor in contact with the stiffener layup.